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    SubjectRe: [PATCH 2/3] MTD: spi-nor: check for short writes in spi_nor_write.
    + linux-spi, Mark

    On Thu, Apr 30, 2015 at 03:38:50PM +0200, Michal Suchanek wrote:
    > My SPI controller driver does not support DMA so writes are truncated to
    > FIFO size.

    Which SPI master driver?

    > Check the amount of data actually written by the driver.

    I'm not sure if we should just reactively use the retlen, or if we
    should be communicating such a limitation via the SPI API. Thoughts?

    Brian

    > Signed-off-by: Michal Suchanek <hramrach@gmail.com>
    > ---
    > drivers/mtd/spi-nor/spi-nor.c | 42 +++++++++++++++++-------------------------
    > 1 file changed, 17 insertions(+), 25 deletions(-)
    >
    > diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
    > index 14a5d23..75904b5 100644
    > --- a/drivers/mtd/spi-nor/spi-nor.c
    > +++ b/drivers/mtd/spi-nor/spi-nor.c
    > @@ -807,7 +807,7 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
    > size_t *retlen, const u_char *buf)
    > {
    > struct spi_nor *nor = mtd_to_spi_nor(mtd);
    > - u32 page_offset, page_size, i;
    > + u32 page_offset, page_remainder, page_size, i;
    > int ret;
    >
    > dev_dbg(nor->dev, "to 0x%08x, len %zd\n", (u32)to, len);
    > @@ -816,36 +816,28 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
    > if (ret)
    > return ret;
    >
    > - write_enable(nor);
    > -
    > - page_offset = to & (nor->page_size - 1);
    > -
    > - /* do all the bytes fit onto one page? */
    > - if (page_offset + len <= nor->page_size) {
    > - nor->write(nor, to, len, retlen, buf);
    > - } else {
    > - /* the size of data remaining on the first page */
    > - page_size = nor->page_size - page_offset;
    > - nor->write(nor, to, page_size, retlen, buf);
    > + /* write everything in nor->page_size chunks */
    > + /* check the size of data actually written */
    > + for (i = 0; i < len; i += *retlen) {
    > + page_size = len - i;
    > + page_offset = (to + i) & (nor->page_size - 1);
    > + page_remainder = nor->page_size - page_offset;
    > + if (page_size > nor->page_size)
    > + page_size = nor->page_size;
    > + if (page_remainder && (page_size > page_remainder))
    > + page_size = page_remainder;
    >
    > - /* write everything in nor->page_size chunks */
    > - for (i = page_size; i < len; i += page_size) {
    > - page_size = len - i;
    > - if (page_size > nor->page_size)
    > - page_size = nor->page_size;
    > -
    > - ret = spi_nor_wait_till_ready(nor);
    > - if (ret)
    > - goto write_err;
    > + write_enable(nor);
    >
    > - write_enable(nor);
    > + nor->write(nor, to + i, page_size, retlen, buf + i);
    >
    > - nor->write(nor, to + i, page_size, retlen, buf + i);
    > - }
    > + ret = spi_nor_wait_till_ready(nor);
    > + if (ret)
    > + goto write_err;
    > }
    >
    > - ret = spi_nor_wait_till_ready(nor);
    > write_err:
    > + *retlen = i;
    > spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_WRITE);
    > return ret;
    > }


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